gecko/layout/build/nsLayoutStatics.h

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Mozilla platform.
 *
 * The Initial Developer of the Original Code is
 * Benjamin Smedberg <benjamin@smedbergs.us>.
 *
 * Portions created by the Initial Developer are Copyright (C) 2006
 * the Mozilla Foundation <http://www.mozilla.org/>. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#ifndef nsLayoutStatics_h__
#define nsLayoutStatics_h__

#include "nscore.h"
#include "nsThreadUtils.h"

// This isn't really a class, it's a namespace for static methods.
// Documents and other objects can hold a reference to the layout static
// objects so that they last past the xpcom-shutdown notification.

class nsLayoutStatics
{
public:
  // Called by the layout module constructor. This call performs an AddRef()
  // internally.
  static nsresult Initialize();

  static void AddRef()
  {
    NS_ASSERTION(NS_IsMainThread(),
                 "nsLayoutStatics reference counting must be on main thread");

    NS_ASSERTION(sLayoutStaticRefcnt,
                 "nsLayoutStatics already dropped to zero!");

    ++sLayoutStaticRefcnt;
    NS_LOG_ADDREF(&sLayoutStaticRefcnt, sLayoutStaticRefcnt,
                  "nsLayoutStatics", 1);
  }
  static void Release()
  {
    NS_ASSERTION(NS_IsMainThread(),
                 "nsLayoutStatics reference counting must be on main thread");

    --sLayoutStaticRefcnt;
    NS_LOG_RELEASE(&sLayoutStaticRefcnt, sLayoutStaticRefcnt,
                   "nsLayoutStatics");

    if (!sLayoutStaticRefcnt)
      Shutdown();
  }

private:
  // not to be called!
  nsLayoutStatics();

  static void Shutdown();

  static nsrefcnt sLayoutStaticRefcnt;
};

class nsLayoutStaticsRef
{
public:
  nsLayoutStaticsRef()
  {
    nsLayoutStatics::AddRef();
  }
  ~nsLayoutStaticsRef()
  {
    nsLayoutStatics::Release();
  }
};

#endif // nsLayoutStatics_h__